1. Field of the Invention
The present invention is related to facilitating flow control.
2. Description of the Related Art
The term “workflow” may be used to describe tasks and data for business processes. The data, for example, may relate to organizations or people involved in a business process and required input and output information for the business process. A workflow automation product allows creation of a workflow model to manage business processes. A workflow engine is a component in a workflow automation program that understands the tasks of each business process in the workflow and determines whether the business process is ready to move to the next task.
A publish-subscribe pattern is a common pattern in distributed applications and describes a pattern in which a publisher (e.g., an application program) generates work requests to be processed by one or more subscribers (e.g., business processes), for example, as part of a work flow. The subscribers that receive the work requests are those that are interested in the work requests and that have registered with the publisher to receive the work requests of interest.
A work request may be described as a business object request because the work request is processed by a business process. For example, a work request may provide data (e.g., employee name and social security number) and a description of what is to be done (e.g., creating, deleting, or updating an entry in a data store).
The publisher may dispatch work requests to an intermediary application program that stores the work requests in queues for each subscriber, and each subscriber retrieves the work requests from an associated queue. Since the intermediary application program holds work requests in each queue until the work requests are retrieved by subscribers, sometimes, a very slow subscriber may not retrieve work requests at a fast rate, leaving many work requests in the queue. This may lead to the queue running out of entries for storing new work requests for that subscriber.
That is, one problem with the publisher-subscriber pattern is the inability to control the delivery of work requests from the publisher so that a queue does not overflow when a subscriber is slow to retrieve work requests from the queue.
Thus, there is a need in the art for an improved technique for processing work requests for a system using a publish-subscribe pattern.